Jet bit



March 30, 1965 D. s. ROWLEY JET BIT Filed Nov. 1, 1962 David S. RowleyINVENTOR.

BY %M) t. QuA

ATTORNEY United States Patent 3,175,629 JET BIT David S. Rowley, SaltLake City, Utah, assignor to Jersey Production Research Company, acorporation of Delaware Filed Nov. 1, 1962, Ser. No. 234,808 5 Claims.(Cl. 175329) The present invention relates to rotary bits for drillingboreholes in the earth and is particularly concerned with an improvedjet bit useful for drilling oil wells, gas wells and similar boreholes.

Jet bits provided with nozzles through which drilling fluid can bedischarged at high velocity against the formation at the bottom of theborehole have been used in the petroleum industry to permit moreeffective scouring of the formation and to promote more efficiententrainrnent of solids in the fiuid. The nozzles employed in such bitsmust have small diameters to achieve the required velocities and aretherefore readily plugged by solid articles of only moderate size. Thisprecludes the injection through such bits of materials normally used tocontrol lost circulation. Each time such a material were employed, thedrill string would have to be pulled from the borehole and the bitremoved. The pipe would then have to be returned to the hole and thelost circulation material injected. After circulation had been restored,

the pipe would have to be pulled from the hole, the bit replaced, andthe drill string again lowered into place. Repeated trips into and outof the borehole are hazardous where lost circulation problems existbecause of the possibility that a blowout may occur during tripping. Forthis reason, the use of jet bits has been restricted.

It is therefore an object of the present invention to provide animproved jet bit for drilling oil wells, gas wells and similarboreholes. A further object is to provide a jet bit which will permitthe injection of lost circulation materials into a borehole without thenecessity of repeated trips to and from the surface. Another object isto provide a jet bit through which lost circulation materials can beinjected without plugging the bit nozzles. Still other objects will beapparent from the following detailed description of bits constructed inaccordance with the invention and from the accompanying drawing, inwhich:

FIGURE 1 is a vertical elevation, partially in section, of a diamond bitconstructed in accordance with the invention; and,

FIGURE 2 is a bottom view of the bit of FIGURE 1.

The bit shown in FIGURE 1 of the drawing is a diamond bit which includesa tubular upper body section 11 of steel or similar metal having anupper shank 12 provided with external threads 13. The upper shank andthreads on the bit shown form a standard A.P. I. tool joint pin which isused to attach the bit to the lower end of a conventional rotary drillstring. Other suitable connecting means may be provided if desired. Theupper body section contains an internal passageway 14 which extendsdownwardly along the longitudinal axis of the tool from an opening atthe top of the upper shank. The diameter of the internal passageway isenlarged below a tapered shoulder 15 located beneath the shank. Lowerbody section 16 is a tubular member attached to the lower end of theupper body section by means of threads 17. An O-ring or similar member18 is set in a groove in the inner surface of the lower body memberbelow the thread to provide a seal between the two sections. The outerdiameter of the lower body section is enlarged below a tapered externalshoulder 19. Threads 20 are provided for attaching the lower bodysection to the cutting head or crown of the bit. The use of an upper anda lower 3,175,629 Patented Mar. 30, 1965 body section as describedpermits ready access to the interior of the bit but is not essential. Insome cases the body member may be made in one piece.

The crown of the bit shown in FIGURE 1 of the drawin-g includes a steelblank 21 provided with threads which mate with those on the lower end ofthe lower body memher. The steel blank and lower body member arenormally welded together after the bit has been assembled, the weldbeing indicated by reference numeral 22. A matrix section 23 is bondedto the lower part of the steel blank in order to provide the desired bitcontour. A typical matrix may consist of a copper-nickelalloy-containing powdered tungsten carbide in quantities sufiicient toconfer the required strength and erosion resistance. Other matrixcompositions and methods for fabricating diamond bits utilizing them aredescribed in the Diamond Drill.

Handboo by I. D. Cumming, 1956 edition, published by J. K. Smit & Sonsof Canada, Limited, Toronto. The portion of the crown formed by thematrix section includes a tapered shoulder 24 and an outer gage surface25 located below the shoulder. The crown is rounded below the gageSurface to form a generally convex drilling face 2 6 containing ashallow cavity located near the longitudinal axis of the bit. Thiscavity, indicated generally by reference numeral 27, results in theformation of a short conical rock projection beneath the bit. This helpscenter the bit in the borehole and provides additional surface for theplacement of diamonds near the bit axis. The diamonds employed ascutting elements are embedded in the gage surface and drilling face andare designated by reference numeral 28. Tungsten carbide chips orsimilar hard, abrasion-resistant particles may be utilized in lieu ofdiamonds in some instances.

rial bonded to the wall of the passageway below the shoulder. Theinternal diameter of nozzle 31 is sufiiciently large to permit thepassage of lost circulation materials which may have to be injectedthrough the bit.

The passageway below the nozzle opens into a discharge port in the lowersurface of the tool. The port is of irregular cross-section as shown inFIGURE 2 of the drawing, thus providing a crows foot for drilling outthe formation beneath the bit axis. watercourses 32 extend from the portacross the bottom of the bit and up the gage surface. Junk slots 33 arespaced at regular intervals around the periphery of the tool to permitthe discharge of large particles dislodged from the formation beneathit. Each junk slot is connected to one of the ports near the bit axis bya short connecting watercourse 34. Jet nozzles 35 are mounted in openingin the crown and discharge into the junk slots. The jet nozzles are madeof tungsten carbide or similar material and are of somewhat smallerinternal diameter than nozzle 31 and the discharge port discussed above.Each of the jet nozzles discharges from an annular recess 36 within thecrown.

An internal nozzle and screen assembly is provided above lower nozzle 31in the bit shown in FIGURE 1.

This assembly forms a first passageway extending longitudinally throughthe tool from the opening in shank 12 to the discharge port in the crownand a second, annular passageway extending from an inlet in the firstpassageway to the openings in the crown within which the jet nozzles 35are mounted. The nozzle assembly shown includes a lower connectingmember 37 which seats against shoulder 30 in the crown. The connectingmember has an external shoulder 38 which bears against the upper surfaceof the portion of the crown surrounding the central passageway 29. AnO-ring or similar member 39 is set in a groove below'the shoulder toeffect a seal between the connecting member and crown. The upper end ofthe connecting member is provided with internal threads 40. Shoulders 41and 42 are located below the threads. A spacer 43 is shown in positionon the lower shoulder 42. An Q-ring 44 is set in a groove between thetwo shoulders and provides a seal between the spacer and the inner wallof the connecting member. 'As will be pointed out in greater detailhereinafiter, the spacer can be replaced with a nozzle of tungstencarbide or similar erosion resistant material if desired A nozzleretainer 45 is located in the nozzle assembly above the lower connectingmember. The retainer is' and is provided with an O-ring 46 to preventthe escape of fluids bet-ween the two. Internal nozzle 47 is seated onan internal shoulder 48 within the retainer. As' can be seen horn thedrawing, the throat diameter of this nozzle is similar to that ofdischarge nozzle 3 1 land is considerably larger than the jet nozzle setinthe lower part of the crown. An O-ring 49 provides a seal between thenozzle and surrounding retainer. Internal threads 50 located above aninternal shoulder '51 permit the connection of a second retainer to theupper end of the retainer described. It will be seen from the drawingthat three additional nozzle retainers 52, 53 and 54 containing nozzles55, S6 and. 57 are provided in the assembly. These are identical to thelower retainer and nozzle and therefore need not be described in detail.

- The uppermost nozzle retainer 54 is connected to the lower end or acylindrical screen retainer 58 by means of threads 59. O-ring 60 is setin a groove above the threads to provide a seal between the two. Thescreen retainer contains longitudinal slots 61 through which fluid maypass outwardly into thc'annular space 62 between the retainer and theinner wall of theupper body section. A cylindrical, slot-ted screen 63seats again-stan internal shoulder 64 in the lower part of the screenretainer and extends upwmdly to the upperend of the retainer above theslots. Screens other than the slotted type shown 7 may be employed. Insome the use of a separate screen may be avoided by providing very smallopenings in member 58 but the use of a separate screen and retainer ispreferred. Annular cap 65 is connected to theupper a closure for theannular space between the screen retainer and the inner wall of theupper body section below tapered shoulder It is not essentialthat thisclosure be absolutely fluid tight and hence no sealing member isprovided. It preferred that the screen, screen retainer,internal'nozzles and nozzle retainer all be made,

of tungsten carbide or a similar erosion-resistant material. It will beapparent that internal nozzle and screen assembly designs other thanthat described above may be employed if desired. In some instances, fiorexample, it may be preferred to mount the internal nozzles and screenwithin a tube of tungsten carbide or similar material held in place nearthe top and bottom of the body member. In other cases it may bedesirable to mount the nozzles and screen in place permanently anddispense with the seals,

threads and f other r eatures required with a replaceable screen andnozzles. These and similar modifications will be apparent to [thoseskilled iii-the art.

During-a rotarydrill-ing operation utilizing the tool shown in thedrawing, drilling fluid is circulated downwardly to the bit throughthe'r drill string to which it is connected; After passing. throughpassageway 14 in the shank of the upper body section, the fluid flowsthrough the opening in annular cap 6-5 on the internal nozzle as sembly.A part of the fluid thus introduced into the nozzle assembly passesdownwardly through the internal nozzles and isdischarged beneath thetool. The internal nozzles reduce the velocity of the fluid so that itemerges from the discharge ports at the bottom of the bit at relativelylow velocity. This avoids undue erosion of the crows foot and adjacentsections of the crown and at the same time permits the of suflicientfluid pressure to secure the required high velocity through the jetnozzles. The use of a'plurality of verti-callyaspaoed internal nozzlesas shown also makes possible the use or considerably larger nozzles thancould otherwise be employed. The number of vertically-spaced nozzlesutilized will depend in part upon the pressure at which drilling fluidis supplied to the bit, the fluid throughput desired, and the pressuredrop across the jet nozzles. If necessary, spacers may be substitutedfor one or more of the nozzles provided. Alternatively, anadditional'nozzle may be substituted for spacer-'43 in the bit shown. Itis generally preferred to employ a maximum number of internal nozzlesand thus maintain the internal nozzle diameters as large as possible.

A part of the fluid introduced into the nozzle assembly through theopening in cap 65 .do'es'not pass through the internal nozzles andinstead is forced through the openings in screen 63 and the slots 61 inthe screen retainer. This fluid flows downwardly through the annularspace 62 between the internal nozzle assembly and the inner wall of theupper body section to the'jet nozzles in the lower part of the bit.Oomparatively little pressure drop occurs in the annular space and hencethe pressure drop across the jet nozzles is This results in thedischargeof fluid at high velocity'against the tor-mation at the bottom of theborehole. Each of the jet nozzles is preferably set at a different angleto the longitudinal axis of the bit so that substantially all of theformation beneath the bitis thoroughly secured by the high velocityfluid as the bit rotates. In most about 50% of the total fluidcirculated o tth-e bit will be dis-charged through the jet nozzles. Thedistribution or fiuidbetween the jet nozzles and theinterhal nozzleassembly can be readily controlled by varying the member of nozzles andthe noz end of the retainer by means of threads 66 to provide zlediameters in the internal nozzle assembly. The addition of an internalnozzle to the assembly will increase the pressure drop through theassembly and hence cause a larger proportion of the total fluid to passthrough the jet-nozzles. The removal of a nozzle from the assembly atthe center of the bit will reduce the pressuredrop and permit a greaterfraction. of. the total fluid to be discharged into the borehole throughthe discharge port near the longitudinal-axis or the tool; In likemanner, a reduction in the. internalnozzlediameters increases thepressure drop in the assembly, resulting in the discharge of more fluidthrough the jet nozzles; while an increase in internal nozzle diameterreduces the proportionate amount of fluid discharged through the jetnozzles.

When the injection of a lost circulation material into vugs or fracturesin the formation surrounding the borehole becomes necessary, thematerial may be entrained in the drilling mud or other fluid at thesurface and circulated downwardly through the drill string withoutinterrupting the drilling operation. -The particles of lost circulationmaterial pass through the relatively-large internal nozzles in the bodyof the bit and are discharged beneath the tool. Thescreen in the upperbody section of the bit prevents entrainment of the particles in fluidpassing through the annular section of the tool to the jet nozzles andhence plugging of the nozzles is avoided. Particles trapped by thescreen are continuously carried away by the fluid passing downwardlywithin the internal nozzle and screen assembly. The.screen is, thusessentially selfcleaning. After the required quantity of lostcirculation material has been injectedintothe formation and circu- Theinvention has been described above in terms of a diamond bit but isequally applicable to rock bits, drag bits and other rotary drillingtools. By simply replacing the diamond cutting elements on the bit shownwith roller cones supported on legs extending downwardly from the bodyor with drag bit blades, the invention can readily be applied to a rockbit or drag bit. The internal nozzle and screen assembly may beidentical to that shown in the drawing. The modifications required tothus adapt the invention to other type bits are minor and will beapparent to those skilled in the art.

What is claimed is:

1. A rotary drill bit comprising:

a body member provided with means for connecting said member to thelower end of a rotary drill string, said body member containing a firstlongitudinal passageway extending from an opening at the upper end ofsaid member to a discharge port at the lower end of said member near thelongitudinal axis thereof and a second longitudinal passageway extendingfrom an inlet in said first passageway near the upper end thereof to anoutlet near the lower end of said body member laterally spaced from saiddischarge port;

means within said first passageway at vertically-spaced intervalsbetween said inlet and said discharge port for increasing the pressuredrop therein and reducing the velocity with which fluid emerges fromsaid discharge port;

means within said second passageway near the lower end thereof forincreasing the velocity with which fluid is discharged from said outlet;

means within said body member for restricting the passage of solids fromsaid first passageway through said inlet into said second passageway;

and cutting elements mounted at the lower end of said body member.

2. A rotary drill bit comprising:

a body member provided with means for connecting said member to thelower end of a rotary drill string and with a lower face for engagingthe formation at the bottom of a borehole, said body member containing afirst longitudinal passageway extending from an opening near the upperend of said member to a discharge port in said lower face near thelongitudinal axis of said member and a second longitudinal passagewayextending from an inlet in said first passageway near the upper endthereof to an outlet in said lower face laterally spaced from saiddischarge port;

means within said first passageway at vertically-spaced intervalsbetween said inlet and said discharge port for increasing the pressuredrop therein and reducing the velocity with which fluid emerges fromsaid discharge port;

means within said second passageway near the lower end thereof forincreasing the velocity with which fluid is discharged from said outlet;

means within said body member for restricting the passage of solids fromsaid first passageway through said inlet into said second passageway;

and a plurality of particulate cutting elements embedded in said lowerface of said body member.

3. A rotary drill bit comprising:

a body member provided with means for connecting said member to thelower end of a rotary drill string and with a crown for engaging theformation at the bottom of a borehole, said body member containing afirst longitudinal passageway extending from an opening near the upperend of said member to a discharge port in said crown near thelongitudinal axis of said member and a second longitudinal passagewayextending from an inlet in said first passageway near the upper endthereof -to a plurality of outlets in said crown laterally spaced fromsaid discharge P a screen within said body member for restricting thepassage of solids from said first passageway through said inlet intosaid second passageway;

a plurality of erosion-resistant nozzles mounted at vertically-spacedintervals in said first passageway above said discharge port and belowsaid inlet for increasing the pressure drop therein and reducing thevelocity at which fluid emerges from said discharge port;

a plurality of jet nozzles mounted in said outlets near the lowersurface of said crown for increasing the velocity with which fluid isdischarged from said second passageway;

and a plurality of diamonds embedded in the lower surface of said crown.

4. A bit as defined by claim 3 wherein at least one of saiderosion-resistant nozzles is removably mounted in said first passageway.

5. A rotary drill bit comprising:

a hollow body member provided with means for connecting said member tothe lower end of a rotary drill string and with a crown for engaging theformation at the bottom of a borehole, said body member containing anopening in the upper end thereof, a discharge port in said crown nearthe longitudinal axis of said member, and a plurality of outlets in saidcrown laterally spaced from said discharge port;

a tubular nozzle and screen assembly mounted within said body member toform a first longitudinal passageway extending through said assembly tosaid discharge port and a second longitudinal passageway extending tosaid outlets from a lateral opening in said assembly near the upper endthereof, said assembly including a screen over said lateral openingtherein and a plurality of erosion-resistant nozzles verticallyspacedbetween said lateral opening and said discharge port to increase thepressure drop therein and reduce the velocity with which fluid emergesfrom said discharge port;

a plurality of jet nozzles mounted in said outlets near the lowersurface of said crown for increasing the velocity with which fluid isdischarged from said outlets;

and a plurality of diamonds embedded in the lower surface of said crown.

References Cited by the Examiner UNITED STATES PATENTS 2,293,259 8/42Johnson 175-340 X 3,112,803 12/63 Rowley 175329 FOREIGN PATENTS 456,14011/36 Great Britain.

CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN HERSH, Examiner.

1. A ROTARY DRILL BIT COMPRISING: A BODY MEMBER PROVIDED WITH MEANS FORCONNECTING SAID MEMBER TO THE LOWER END OF A ROTARY DRILL STRING, SAIDBODY MEMBER CONTAINING A FIRST LONGITUDINAL PASSAGEWAY EXTENDING FROM ANOPENING AT THE UPPER END OF SAID MEMBER TO A DISCHARGE PORT AT A LOWEREND OF SAID MEMBER NEAR THE LONGITUDINAL AXIS THEREOF AND A SECONDLONGITUDINAL PASSAGEWAY EXTENDING FROM AN INLET IN SAID FORST PASSAGEWAYNEAR THE UPER END THEREOF OF AN INLET NEAR THE LOWER END OF SAID BODYMEMBER LATERALLY SPACED FROM SAID DISCHARGE PORT; MEANS WITHIN SAIDFIRST PASSAGEWAY AT VERTICALLY-SPACED INTERVALS BETWEEN SAID INLET ANDSAID DISCHARGE PORT FOR INCREASING THE PRESSURE DROP THEREIN ANDREDUCING